I just got two algea eaters to live with my two bettas. they are in a 2.5 gal tank, and after I cleaned the tanks I put the algea eater in first.

However when I put my betta fish (Zeke in this case) he circled around the other little one and nipped at him, once he did that the algea eater ran away.

I watched them for a few minutes and everytime Zeke gets near the little algea eater his gills start to flare, somtimes he'll nip at him, others he chases him around the tank for a second then goes back to swimming like he normally does

I have since taken him out to write this post, I do not want the little algea eater killed

should i try to reintroduce zeke later? or take the algea eaters back to petsmart?

Alright, thankyou very much for the advise. I was prepared to change tank sizes if need be but the algea eater is very small and my other betta fish (Flare) has taken to his new little buddy quite well. He just kinda looked at him as if he were perplexed there's someone else in the tank for a few times but other than just stopping for a second to watch his little buddy, Flare is just as normal. So that means I need to take one back but at least I can give one little buddy a home.

Thanks for the help :)

Zeke is just a mean little betta fish that needs his own space lol, atm he is watchin me type it and watchin the screen as if he's agreeing (if betta's have that mental capacity)

IMO/E-2.5gal tanks do not provide enough room to support more fish along with the Betta. Even though the other Betta seems fine with the other fish-I would recommend that you take both back to the fish shop.

The stress from either fish-Betta and/or algae eater can cause compromised immune response and then its just a matter of time before things go bad.

Why do you feel the need to add algae eaters to your tanks-Do you know what species of fish they are.

If you added them due to algae problems-it is important to figure out the cause of the algae. Remembering that some species of algae can be a sign of a healthy system and normal.
Most algae eater only eat some types of algae and you will still need to manually remove problem algae along with water changes. A closed system can't support the nutritional needs and they will need supplemented feeding-This can also cause problems-since Betta tend to be piggies and will eat the other fish food that often end badly for the Betta....